WebAPI接口 上传文件资源

1.API接口 异步请求
 [System.Web.Http.AcceptVerbs("GET", "POST")]
        [HttpPost]
        public  Task<Business> PostReport()
        {
            Business bussiness = new Business();
            // 检查是否是 multipart/form-data 
            if (!Request.Content.IsMimeMultipartContent("form-data"))
            {
                Business business = new Business();
                business.message = 0;
                business.messageDetail = "数据形式错误";
            }
            //文件保存目录路径  上传图片
            string url = Request.RequestUri.Host;
            string SaveTempPath = "/Content/images/ReportImg/";
            String dirTempPath = HttpContext.Current.Server.MapPath(SaveTempPath);
            if (!Directory.Exists(dirTempPath)) Directory.CreateDirectory(dirTempPath);//如果目录不存在怎新建
            // 设置上传目录 
            var provider = new MultipartFormDataStreamProvider(dirTempPath);
            List<string> imgList = new List<string>();//图片路径
            var task = Request.Content.ReadAsMultipartAsync(provider).
               ContinueWith<Business>(o =>
               {
                   foreach (MultipartFileData file in provider.FileData)
                   {
                       string orfilename = file.Headers.ContentDisposition.FileName.TrimStart('"').TrimEnd('"');
                       FileInfo fileinfo = new FileInfo(file.LocalFileName);
                       //最大文件大小 
                       int maxSize = 10000000;
                       if (fileinfo.Length <= 0)
                       {
                           bussiness.message = 0;
                           bussiness.messageDetail = "请选择上传文件。";
                       }
                       else if (fileinfo.Length > maxSize)
                       {
                           bussiness.message = 0;
                           bussiness.messageDetail = "上传文件大小超过限制。";
                       }
                       else
                       {
                           string fileExt = orfilename.Substring(orfilename.LastIndexOf('.'));
                           //定义允许上传的文件扩展名 
                           String fileTypes = "gif,jpg,jpeg,png,bmp";
                           if (String.IsNullOrEmpty(fileExt) || Array.IndexOf(fileTypes.Split(','), fileExt.Substring(1).ToLower()) == -1)
                           {
                               bussiness.message = 0;
                               bussiness.messageDetail = "上传文件扩展名是不允许的扩展名。";
                           }
                           else
                           {
                               String ymd = DateTime.Now.ToString("yyyyMMdd", System.Globalization.DateTimeFormatInfo.InvariantInfo);
                               //String newFileName = DateTime.Now.ToString("yyyyMMddHHmmss_ffff", System.Globalization.DateTimeFormatInfo.InvariantInfo);
                               string newFileName = Guid.NewGuid().ToString();

                               fileinfo.CopyTo(Path.Combine(dirTempPath, newFileName + fileExt), true);
                               
                               fileinfo.Delete();
                               bussiness.message = 1;
                               bussiness.messageDetail = "上传成功。";
                               imgList.Add(SaveTempPath + newFileName + fileExt);
                           }
                       }
                       if (bussiness.message == 0)
                           return bussiness;
                   }
                   // 读取项目参数并保存
                   if (provider.FormData != null && provider.FormData.Count > 0)
                   {
                       #region 读取请求参数
                       Dictionary<string, string> dic = new Dictionary<string, string>();
                       foreach (var key in provider.FormData.AllKeys)
                       {
                           foreach (var val in provider.FormData.GetValues(key))
                           {
                               dic.Add(key, val);
                           }
                       } 
                       #endregion
                   }
                   return bussiness;
               });
            return task;
        } 
        #endregion
2.后台调用方法

  using (var client = new HttpClient())
            {
                using (var content = new MultipartFormDataContent())
                {
                    // Make sure to change API address

                    client.BaseAddress = new Uri("http://192.168.1.87:8082/");
                    //client.BaseAddress = new Uri("https://localhost:44301/");
                    // Add first file content
                    var fileContent1 = new ByteArrayContent(File.ReadAllBytes(@"C:\Users\admim\Desktop\js\images\bci.jpg"));

                    fileContent1.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                    {
                        FileName = "bci1.jpg"
                    };
                    // Add Second file content

                    var fileContent2 = new ByteArrayContent(File.ReadAllBytes(@"C:\Users\admim\Desktop\js\images\bci.jpg"));

                    fileContent2.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                    {
                        FileName = "bci2.jpg"

                    };
content.Add(fileContent1);

                    content.Add(fileContent2);
                    //content.Add(fileContent3);
                    //content.Add(fileContent4);
                    //content.Add(fileContent5);

                    //content.Add(fileContent3);
                    // Make a call to Web API

                    #region请求字段值
                    content.Add(new StringContent("4"), "FCoachProjectID");
或者 
      HttpContent httpContentLogin = new StringContent("{\"name\":10005005,\"password\":\"aaaa\"}");
                    httpContentLogin.Headers.ContentType = new MediaTypeHeaderValue("application/json");
    var result = client.PostAsync("/api/TeacherCoach/PostReport", content).Result;